Hi all, Had the floors of the main areas of my house house (on a concrete slab approx 16 sqm) relevelled with screed approx 1 year ago at a depth of up to 70mm in parts. The screed was graded down the house. One long hairline crack running the length of the living area has emerged since and the screed crumbles into powdery gravel if you dig or scratch about. It also sounds hollow along this line when its knocked on. Going to have pvc hybrid floorboards with waterproof backing and 5G click system laid on top in a month or so. Question is, will we have problems with the flooring later down the line? Note: the house was built on clay soil and was subjected a few years ago to ongoing leaking water issues resulting in subsidence on one side of the house. The plumbing issues have been fixed, the soils are stabilised and no movement of soils outside of tolerance levels have been recorded for for over a year. The crack is in the direction the floorboards will be laid and is close to the area where subsidence and movement of the slab occurred previously. Thanks!
You can't lay over if it's cracked and sounds hollow, it'll need taking up and redoing properly, no good trying to cover over a loose slab as it'll damage your flooring especially being a click system.
Dig it out and put a new screed in or lay over and hope for the best. Floors will only be as good as the subfloor beneath
